the smoke comes and goes almost on a 12 hour cycle. It will clear out midday and we will go to bed with the windows open for the delta breeze, but then be awakened during the early morning hours with smoke so thick vis is less than a quarter mile, some mornings only a few hundred yards.

It's the heat/cool cycle of the day. The full heat of the day causes an uplift of air over the fire, then it all comes back down in the wee hours of the morning. It is starting to lift now.